This invention relates to a printer used to produce images (mostly, though not exclusively, photographic images) in black, but more often in colour, on a printing medium (for example, a sheet of paper, treated or untreated, or a sheet of plastic, of variable format) by means of the ink jet technology (either thermal or piezoelectric type), and, more particularly, to a printer provided with a removable and interchangeable paper cassette containing a plurality of said printing media, having the same format and the same physical-chemical characteristics.
Printers of the type described above are known in the art, that use printing means generally in the form of ink jet print heads, in some cases capable of printing a whole line at a time (line heads), but more often mounted by fixed or interchangeable means on a scanning carriage.
The composition and general mode of operation of an ink jet printer, as also those of the associated ink jet printhead, are already widely known in the sector art, and will not therefore be described in detail herein, the description accordingly being limited to a more detailed account of some characteristics of relevance to the understanding of the present invention, taking as a reference the example of a colour printer provided with scanning carriage and using the thermal ink jet technology.
A typical ink jet colour printer of the type indicated above schematically comprises:
a system, selectively actuated by a motor, for the feeding of the sheet of paper upon which the image is to be produced, so that the feeding occurs in a given direction in discrete steps (line feed),
a movable carriage, sliding on ways in a direction perpendicular to that of feeding of the sheet, selectively driven by a motor to accomplish an outward motion and a return motion across the entire width of the sheet itself,
a printhead removably affixed to the carriage, comprising a plurality of emission resistors deposited on a substrate (usually a silicon wafer) and arranged inside cells filled with ink, individually connected to a corresponding plurality of nozzles, through which the head is able to emit the droplets of ink contained in a tank, which may be an integral part of the head, in the case of the so-called monobloc or disposable heads; or it may be interchangeable, being removably fitted on the head, in the case of the so-called refillable type heads. The tank contains at least three different inks, corresponding to the primary colours, cyan, magenta and yellow,
an electronic controller which, on the basis of the information received from a computer the printer is connected to and of the presettings effected by the user, selectively controls both the above-mentioned motors and the printhead, causing therein, through the selective heating of the resistors, the emission of the droplets of ink against the surface of the printing medium, generating a visible image thereon.
The presettings that may be effected by the user, as is known in the sector art, concern particularly the printing mode that is to be implemented, in order to produce a printout having a printed colour quality, assessed in terms of uniformity, brilliance, correspondence with the original and separation between adjacent colours, consistent with the use that is to be made of the document and the type of printing medium upon which the document in question is to be produced.
For example, the presettable printing modes, in order of increasing quality and decreasing economy, are those indicated with terms such as xe2x80x9cdraftxe2x80x9d, xe2x80x9ceconomyxe2x80x9d, xe2x80x9cstandardxe2x80x9d, xe2x80x9chigh qualityxe2x80x9d or xe2x80x9cpresentationxe2x80x9d. These modes control the presetting of suitable factors such as, for example, the resolution of the image decomposition grid (for example, 300xc3x97300 or 600xc3x97600 dots/inch2); the direction of scanning during printing (for example, monodirectional or bidirectional); the consumption of ink (for example, by reducing the number of dots printed from 100% to 75%, to 50% or to 25%); the inking speed (for example, by application of a technique known as xe2x80x9cshinglingxe2x80x9d, i.e. printing a line with a variable number of head passes, involving one or more nozzles), for example, low speed with shingling of 30%, average speed with shingling of 50%, or high speed without shingling.
The five different printing modes described above are represented in summary form by way of example in table T1 below:
The type of printing medium on which to produce the document can be selected by the operator from a wide range of options; for example, it may be plain paper, of the type used in photocopiers; glossed paper, surface-treated on one side only for a glossy finish; coated paper, with the same characteristics as glossy paper, but with a very smooth surface; transparent glossy plastic, for use with a projector; all of different formats and different weights and thicknesses.
The final document quality depends on the selected combination of printing mode and printing medium. It will be clear, however, from the above that the large number of variables represents a factor of confusion for the operator, giving rise to a considerable degree of difficulty in making the right choice, even if hard-copy or on-line manuals are available to guide the operator in making this choice.
All the more so when the user of the printer is not a professional user, which is exactly the case with the non-professional colour printers called xe2x80x9cphotographicxe2x80x9d that have recently appeared on the market. These are intended for a general, not necessarily adult, public for the printing of photographs produced with digital cameras, known in the art, and which, instead of producing a chemical image on a negative or positive film, produce a digital file of a format suitable for being printed by a colour printer, usually thermal or ink jet type; or, alternatively, for the printing of photographs or slides produced using traditional methods, but subsequently digitized using known type scanner equipment.
Selection of a wrong combination of printing mode and type of medium produces poor results, with a consequent waste of materials (ink and media) and leaves the user dissatisfied.
The patent JP 3,240,541 discloses the use of a sensor to detect the medium width, in order to modify printing parameters accordingly.
The U.S. Pat. Nos. 5,067,835 and 5,053,814 disclose the use of a paper cassette having a bar code or similar to identify some characteristics of the medium, or order to optimize the printing output.
However, the cited prior art documents leave some problems unsloved, because the number of informtion items is limited by the number of sensors or by the extension of the code, and some characteristics of the medium are lost. The control of the printing parameters based on said informations cannot keep into account non standard variables, e.g. a special type of coating, a cross-correlation amongst some variables, or a combinating of variables leading to a surprising behavior of the printout.
The scope of this invention is to define an ink jet colour printer that avoids the problem described above, ensuring that the correct combination is always made between printing mode and type of medium on which to print the photographic image, thereby eliminating the problems of poor quality of the printed image and wasted materials due to the user""s lack of skill.
Another scope of the invention is to define an ink jet colour printer provided with a removable and interchangeable cassette for accommodating the printing media, marked with a code for the type of medium it contains; and with a system for reading this code for the corresponding automatic setting of the correct printing mode in relation to the type of medium.
A further scope of the invention is to define an ink jet colour printer provided with a printhead interchangeable with others of different characteristics; with a system for recognition of the specific characteristics of the printhead in the machine; with a removable and interchangeable cassette for accommodating the printing media, marked with a code for the type of medium it contains; and with a system for reading this code for the corresponding automatic setting of the correct printing mode in relation both to the type of printhead and to the type of medium.
A further scope of the invention is to mark such cassette with a code identifying all the characteristics of the medium as a whole, thereby allowing the direct selection of the right printing mode also in presence of non standard variables, cross-correlations amongst some variables, or combinations of variables leading to a surprising behavior of the printout.
An ink jet colour printer, characterized as defined in the main claim, is capable of fully attaining the above scopes.
These and other scopes, characteristics and advantages of the invention will become clear from the following description of a preferred embodiment, provided by way of a non-exhaustive example and with reference to the accompanying drawings.